Airborne environmental and engineered nanoparticles (NPs) are inhaled and deposited in the respiratory system. The inhaled dose of such NPs and their deposition location in the lung determines their impact on health. When calculating NP deposition using particle inhalation models, a common approach is to use the bulk material density, ρb, rather than the effective density, ρeff. This neglects though the porous agglomerate structure of NPs and may result in a significant error of their lung-deposited dose and location. Here, the deposition of various environmental NPs (aircraft and diesel black carbon, wood smoke) and engineered NPs (silica, zirconia) in the respiratory system of humans and mice is calculated using the Multiple-Path Particle Dosimetry model accounting for their realistic structure and effective density. This is done by measuring the NP ρeff which was found to be up to one order of magnitude smaller than ρb. Accounting for the realistic ρeff of NPs reduces their deposited mass in the pulmonary region of the respiratory system up to a factor of two in both human and mouse models. Neglecting the ρeff of NPs does not alter significantly the distribution of the deposited mass fractions in the human or mouse respiratory tract that are obtained by normalizing the mass deposited at the head, tracheobronchial and pulmonary regions by the total deposited mass. Finally, the total deposited mass fraction derived this way is in excellent agreement with those measured in human studies for diesel black carbon. The doses of inhaled NPs are overestimated by inhalation particle deposition models when the ρb is used instead of the real-world effective density which can vary significantly due to the porous agglomerate structure of NPs. So the use of realistic ρeff, which can be measured as described here, is essential to determine the lung deposition and dosimetry of inhaled NPs and their impact on public health.

中文翻译：

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吸入环境和工程纳米粒子的有效密度及其对肺沉积和剂量测定的影响

空气中的环境和工程纳米颗粒 (NP) 被吸入并沉积在呼吸系统中。此类纳米颗粒的吸入剂量及其在肺部的沉积位置决定了它们对健康的影响。当使用颗粒吸入模型计算纳米颗粒沉积时，常见的方法是使用散装材料密度 ρb，而不是有效密度 ρeff。这忽略了纳米粒子的多孔团聚结构，并可能导致其肺沉积剂量和位置的显着误差。在这里，使用多路径粒子剂量测定模型计算了人类和小鼠呼吸系统中各种环境纳米颗粒（飞机和柴油黑碳、木材烟雾）和工程纳米颗粒（二氧化硅、氧化锆）的沉积量，考虑了它们的实际结构和有效密度。这是通过测量 NP ρeff 来完成的，我们发现 NP ρeff 比 ρb 小一个数量级。在人类和小鼠模型中，考虑到纳米粒子的实际 ρeff，可将其在呼吸系统肺部区域的沉积质量减少至两倍。忽略 NP 的 ρeff 不会显着改变人类或小鼠呼吸道中沉积质量分数的分布，该分布是通过将沉积在头部、气管支气管和肺部区域的质量除以总沉积质量标准化而获得的。最后，以这种方式得出的总沉积质量分数与柴油黑碳人体研究中测量的结果非常一致。当使用 ρb 代替现实世界的有效密度时，吸入颗粒沉积模型会高估吸入纳米颗粒的剂量，而现实世界的有效密度可能由于纳米颗粒的多孔团聚结构而发生显着变化。因此，使用可按此处所述进行测量的实际 ρeff 对于确定吸入纳米颗粒的肺部沉积和剂量测定及其对公众健康的影响至关重要。